Akai GX-635D takedown procedure and a question...

[analog addict]

Thought I would do a little primer on disassembly of this deck, since one of our members was kind enough to loan me a service manual....

First, unplug the unit, and take off the wooden side panels. Each side panel is held in by 4 screws and recessed washer mounts.

Looking back on it, I suppose it would have been more effective to start this with the unit standing up, since I wound up repositioning it later.

Next, take off the metal side plates.

My unit only had the two screws indicated by the arrows. However, I don't think anyone had been in the unit by the way some of the screws had that snap to them when breaking loose.

The S.M. tells you to take the bottom off next, but since I wanted the feet on for the time being, I took off the back next...

The four small screws (indicated by the red arrows) and the feet (yellow arrows) all need to come off.

After looking in the back, I could tell that I wasn't going to be able to get to the mechanicals without taking the face plate off...

 

[analog addict]

Taking the plunge...

I had a little trepidation looking at the front panel, because there is a LOT of stuff to deal with, but taken in stages it was no problem...

OK, first the knobs and head cover....

All the knobs (red arrows) pull straight off with gentle traction, except the Timer/Lock knob. This will require a small Allen wrench for the set screw on the shaft.

Also, the Rec level nested knobs are a two out of three deal in that the bottom collar stays put until the bottom face plate comes off. Only attempt to remove the knob and the first collar. (See picture below)

The outer head cover comes off next by undoing the larger hex bolts, and by taking the pinch roller cover off. The roller cover unscrews by holding the rubber with one hand and twisting the cover with the other. (yellow arrows)




The head cover base is next, and it comes off by unscrewing the two Phillips head screws on the top portion, the two hex bolts on the lower portion, and by removing the pinch roller. I should have taken better pictures at this point, but I was thinking about the take down and also half watching the Superbowl, so I was lax....

Anyway, all these parts are obvious, because the head cover base is a solid piece of grey plastic, and the connectors are all very evident. (see red arrows)

The pinch roller is secured by a nut, which when torque is applied, spins the pinch roller up towards the heads. Once the roller has come to the end of its travel, a little extra twist will break the nut loose.

 

[analog addict]

Next....

...Undo the 8 hex bolts (red arrows).

Remove the top portion of the face plate by carefully lifting up the edges. Remove the bottom portion similarly, except the right lower edge will require a bit more effort and attention because of the bottom Rec Level collars. However, everything will slide off with the right amount of elbow grease.




This is what you're left with.....

And, working the pinch roller mechanism, I noticed this....

Why would anyone want to put Elmer's glue on a sliding mechanism? Oh right, that used to be grease......:thumbsdn:

 

[analog addict]

Alright!

..so I think I have it figgered out. I take a knife and carefully scrape away the old solidified grease. Hmmmm... still sticking..What gives?

After burning the wood for a few more minutes, I got the bright idea that there may be other areas of congealed grease that I hadn't addressed. I took a peak under the head block, and lo and behold, more concrete. Unfortunately, this meant that I needed to take the head block off to get at the rest of the mechanism.....great....:sigh:

However, this is really not a big deal, with the main point being not to bring ANY magnetized tools near the heads themselves. There are only 4 screws holding the head block. ( red arrows)

However, once I got the screws out, it became evident that the wire connections were not long enough to lift the head block completely out of the way, so I did the easy thing, and just clipped the wire ties holding the 2 wire bundles connected to the head block. If you so desire, these wires are attached by slip on pin connectors, so the entire head block can be removed.

Look what I found!....:nono:

 

[analog addict]

Almost there....

I think I've found the source of the continued binding of the mechanism. So now what?

With a small flat head screw driver, the C-collars for all three sliding points can be slipped off, and the sliding arm can be wiggled off its track.

However, it can't be removed entirely without removing the tension springs that are attached to it (red arrows)

 

[analog addict]

The easy way out....

Rather than risking stretching the springs, I worked with the springs still attached. I removed all the old grease from the teflon support under the sliding arm and regreased it with some white grease I just happened to have lying around....

I then cleaned the front and back of the slots on the sliding arm and regreased them. In this picture the right slot is regreased and the left slot is cleaned and awaiting grease

Here is the arm replaced awaiting the C-collars to be returned

I tested the mechanism, and voila! it slid slick as snot. I put everything back together in reverse order, did a very quick clean on the heads, and with a push of a button, had a functioning GX-635D. Now for the one thing I did eventually find wrong.....

 

[analog addict]

I was hoping everything would be 100%

Unfortunately, I'm only getting very low sound out of the reverse playback. If I turn up the head phone volume, I can hear music in both channels, but nowhere near the volume as playing forward. Is this just a head adjustment, or is it more likely one of the dreaded transistor failures?

I'll post the cosmetic issues and solutions a little later. I gotta get back to work....

Comments and ideas please!....:thmbsp:

 

[mpbird]

:ntwrthy: :ntwrthy:

Awesome! Thanks for posting this. I'm gathering all the info I can on this deck as I need to tackle mine soon. This will be very helpful.

I've noticed quite a bit of traffic on the board concerning the GX-635. Hopefully the moderator can find some way to make sure this isn't lost in the shuffle as time passes. Seems "Sticky" worthy to me.

 

[analog addict]

No worries...

:ntwrthy: :ntwrthy:

Awesome! Thanks for posting this. I'm gathering all the info I can on this deck as I need to tackle mine soon. This will be very helpful.

I've noticed quite a bit of traffic on the board concerning the GX-635. Hopefully the moderator can find some way to make sure this isn't lost in the shuffle as time passes. Seems "Sticky" worthy to me.

You're welcome. Every once in awhile I try and refill the karma banks and do a detailed thread on something I'm working on in the hopes that it might help someone else out down the road. I've done the same thing with a Teac RTR in this forum.

A sticky really isn't necessary or even warranted, since each deck is different as to it's disassembly. Instead if the model number is clearly listed in the title, it's available via the search function....:thmbsp:

 

[analog addict]

Now for the cosmetic rehab....

The other thing about this deck was that at some point in its life it belonged to a smoker, since it came with a nice Marboro golden patina.

Here's an example of what I mean....

and on the bottom portion of the face plate, you can see the streaks of tar...

The normal Simple Green bath wasn't really doing the job, so i decided to try something a bit more radical....


I took some 4-0 steel wool, and despite many of these pieces being plastic underneath, the metallic finish cleaned up nicely with some judicious polishing....

[/IMG]



Here's the 2 PLAY buttons, one clean one dirty. Can you tell which is which?

BTW all the button controls come out easily. The power button and smaller function buttons pop out with a little pressure from the front. Just be careful not to lose the spring that comes out with them.

The bigger buttons like the PLAY button come out by gently squeezing the two tabs that hook at the back side of the button, and then gently pushing them out from the rear.




Here are the two largest collar knobs. They actually cleaned up really well. I think the picture shows the reflection of the dirty knob off the clean one....:thumbsdn:

Lastly the bottom faceplate...I had to stick with Simple Green on this part, because I wanted the lettering to stay where it was put. So I added a big jar of elbow grease, and eventually it came clean....:yes:

Despite the fresh grubby fingerprints, I think you can tell that the yellow coating is gone....:thmbsp:

 

[jan_stevns]

To make it short : I'm impressed

 

[glreltub]

Great post. You provided a lot of very useful information. I have my 635d tore apart right now, trying to figure out why I have no out put in either channel. Where can you find a service manual?

 

[AAA3330]

Very well done.:yes: Thanks for sharing. I have a GX-646, but have never seen this one in the nude. I've used Flitz polish to clean stubborn faceplates like this with excellent results.:thmbsp:

 

[analog addict]

Great post. You provided a lot of very useful information. I have my 635d tore apart right now, trying to figure out why I have no out put in either channel. Where can you find a service manual?

Another AK'er sent it to me, and I scanned it. I've been having trouble converting it to a pdf so that it can be posted in the Dig Doc's forum. Anyone have any ideas?

Right now it's a series of jpeg images in a word doc, so it's about 255 Meg large....

If someone can convert it and send it to Victor for posting, I'll make a CD-R and send it along....:yes:

 

[Tinman]

Great post. Should be a sticky.

 

[Tracker8]

GX-635 D/DB Manual

I got my GX-635D manual at this site:

http://www.hifiengine.com/manuals.shtml

My deck only played one channel forward and neither channel in the reverse direction. Contact cleaner/lubricant on the rec/play switch in the bottom of the deck fixed the problem. It is solenoid driven by a long steel bar that spans the unit.

 

[Numistrek09]

One day i hope to own one of these machines, or a 636, so i'm definitely saving this thread. And if you do get that manual converted, tell me how you did it. I have several i'd like to donate to the database, but i have no ideal how to take jpeg scans and make them into pdfs.

Ohh, and keep that manual in color. I am so tired of the black and whites that blend everything together.

 

[geartech]

Wow on the thread - great work. Your karma banks surely have been recharged. :tresbon:
I dont know what your playback issue is, but have heard that about the contact cleaner working in the play switches of other Akai decks.
I can help with the converting manuals to PDF... I use Word, scanning the pages in as images. Then, I print to pdf using a free product called PDF995.
Go to www.pdf995.com and its a free download. It installs as a printer. So then you can print that Word doc to "pdf995" instead of your normal printer and it will create a pdf of that file. Using the free version it will pop up a screen or two that are more or less ads for itself, just to annoy you to purchase the 'not free' version. Other than that, its slick, I use it at work quite often. We can start a thread on this if anyone has questions, I dont want to hijack this thread...

 

[DougMac]

Great post. Thanks for sharing the info. I agree it should be a sticky, joining the ranks of the Teac X-1000R that helped me resurrect my pawn shop find.

I'm thinking your playback problem is not transistor related. I would assume that the unit is designed to send the signal from the heads through the same electronics, no need to have two different circuits, just switch from one head to the other. Tracing the schematic should shed some light on the matter.

 

[Andyman]

I peeked in here because I did have to deal with the transistor replacement and was curious if you dealt with that. And I would have to agree with Doug above; I can't see 4 amplifiers in there.

That being said, the transistor replacement is actually pretty easy and much less involved than your teardown is. All the pads are accessible from the outside once the case is removed, and most can be accessed with a curved forceps or hemostat. I think there were a couple I had to pull a linkage to get to, but otherwise it was a relatively easy job, and this is coming from a guy who never replaced transistors before in his life.

I did solder them all in backwards the first time though as I thought I was looking down on them, not up in my reference...